<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .outer {
            width: 500px;
            height: 500px;
            margin: 50px;
            padding: 30px;
            background-color: greenyellow;
            border: 1px solid black;
        }

        .inner {
            width: 90px;
            height: 90px;
            margin: 50px;
            background-color: blue;
            padding: 30px;
            border: 1px solid black;
        }
    </style>
</head>

<body>
    <div class="outer">
        <div class="inner"></div>
    </div>
</body>

</html>